A sand dune, found in deserts and beaches, is formed by what type of erosion? * -Wind
-Gravity
-Water
-Ice

wind

Explanation:

Sand dunes form when the wind deposits sand.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

the answer is c.) there is a warm front in region a and a stationary front in region b.